1. Field of the Invention
The present invention relates to an alternator mounted on a vehicle such as a passenger car, a truck or the like.
2. Description of Related Art
A slant nose type vehicle has recently been required to decrease a running resistance in the vehicle or to improve a field of vision for a driver. Further, a wide accommodation space of a vehicle compartment has recently been required to improve comfortability while driving. These requirements narrow an engine room space. In the engine room, an engine, an exhaust pipe including an exhaust manifold, an alternator and the like are disposed.
An exhaust gas is generated in the engine and passes through the exhaust manifold. Finally, the gas is output to the outside through the exhaust pipe. The alternator has various electrical components such as a regulator. The alternator generates an electric power from a rotational force transmitted from the engine and outputs the electric power through a vehicle harness. This electric power is accumulated in a battery or is supplied to current consumers. The regulator receives a control signal from an electric control unit (ECU) through another vehicle harness and controls the generation of the electric power.
The exhaust pipe including the exhaust manifold is heated at a high temperature by the exhaust gas. To efficiently cool the exhaust pipe, the pipe is disposed on a front side of the engine so as to receive a wind from the outside of the vehicle as a cooling air. Therefore, the exhaust pipe is inevitably placed so as to be close to the alternator. In this case, the exhaust pipe gives a radiation heat or/and a transfer heat by conduction to the regulator and the vehicle harnesses of the alternator, so that there is a high probability that the vehicle harnesses and/or the regulator will receive heat damage from the exhaust pipe.
When the regulator is heated at a high temperature due to the radiation heat or the transfer heat by conduction, the regulator cannot continue normal operation. For example, in this case, the alternator is not correctly controlled by the regulator. When the vehicle harness is melted and cut off due to the radiation heat or the transfer heat by conduction, the alternator cannot receive any control signal or cannot supply the electric power to the current consumers and the battery.
To prevent the alternator from receiving any heat damage from the radiation heat or/and transfer heat by conduction given from the exhaust manifold, Published Japanese Patent First Publication No. H08-284680 discloses a thermal protection system wherein a thermal shield plate is fixed to an engine. This plate prevents a wind heated on the exhaust manifold from blowing against the alternator. Therefore, the plate thermally protects the alternator. Further, Japanese Patent Specification No. 2841702 discloses a thermal protection system wherein a duct is disposed on a rear side of an alternator in a vehicle so as to be close to an engine. A cooling air received from the outside passes through the duct and cools the alternator. Therefore, the alternator can efficiently be cooled.
However, in these thermal protection systems, the number of constitutional elements in the vehicle is increased, so that the number of assembling works is inevitably increased. As a result, a cost for manufacturing the thermal protection system is undesirably increased.